When doing legal writing, it's easy to trip yourself up by trying to select words that match an imaginary legal style that you're hearing in your "writer's ear." If you're writing a brief, for example, you might be striving for a sort of serious, elevated tone that you've picked up from reading cases. But nothing you write seems to measure up. What can you do?
Your mistake comes from adopting a tone and style that really has nothing to do with good legal writing. Rather than striving for clarity and understanding in the fewest words possible, you've adopted a way of writing that doesn't come naturally to anyone. You've elevated style over substance even before you've settled on the substance. And the style you've selected isn't too great either. The elevated, serious tone you're striving for exists mostly in your mind. You're probably better off leaving it out of your brief.
How do you do this in practice? There's an easy trick for getting yourself in the right state of mind for banging out a first draft quickly. Set down your brief and pretend instead you're writing a letter. "Dear Judge" the letter might begin. Or "Dear Senior Partner." If that's still too intimidating for you, pretend you're writing a letter to the person in the next office. Start your draft again from the beginning. Try to communicate what you are trying to say in a way that comes naturally to you--that is, exactly as you do when you're writing a letter or an email to someone you know.
Once the draft is going--and it will get going--you can revert back to the form the finished piece is supposed to take, free of the mental block that was making the words so difficult to get down in the first place.
For more on writing first drafts, see my article from the Illinois Bar Journal, "First Drafts Made Easy" (originally published 6/03, now reprinted on my law firm's website).